Parkinson's disease is a neurodegenerative disease characterised by the progressive deterioration of motor skills, affecting about 4 million people worldwide. Parkinson's patients suffer from increasing difficulties in initiating movement, rigidity in arms and legs, as well as tremors. Although the specific cause of Parkinson's disease is unknown, it has been shown that the disease is associated with the degeneration of specific dopamine-containing neurons in a region of the brain known as the substantia nigra, which is believed to be involved in the coordination of movement.
One existing treatment is L-DOPA therapy, alone or combined with e.g. dopamine agonists. However, after three to five years of L-DOPA therapy, involuntary motor disturbances (dyskinesia) may appear.
Another treatment is the use of monoamine reuptake inhibitors (such as dopamine reuptake inhibitors) whereby the existing dopamine level in the synaptic cleft is increased.
A further possible therapy is the use of neurotrophic compounds which give a neuroregenerative effect on lesioned and damaged neurons.
A still further treatment suggested is the use of adenosine A2A receptor antagonists, which result in an enhanced dopaminergic activity. Furthermore, adenosine A2A receptors and their relation to neuroprotection have been discussed (Ongini, E. et al. (1997) Adenosine A2A receptors and neuroprotection, Ann NY Acad Sci 825:30–48).
There is a continued strong interest in the development of a more selective and effective therapy with fewer side effects for the treatment of patients with Parkinson's disease.